speaker thud

[sxc_sound]

hey guys, iv had my install in my vt for about 4 weeks now, i have managed to get rid of all my interference and high pitched noise, but when my head unit turns on there is a little squeal and when it turns off all of the speakers give a big thud, you can see the cones in the speakers move when it makes this noise.

Just wondering what could be causing this?

[rcnugget]

my subs do this as well I think its something to do with the mosfet in your amp/hu dropping power

[Philthy]

My subs used to do this about once a week, then I pulled the amp out for something and since putting it back in it hasn't done it again. Make sure you have a good earth

EDIT: I'm assuming you are running amps?

[sxc_sound]

yes, there are 2 amps, its mainly just the rear speakers and subs that make the noise, iv read some stuff and some people think it may be the gain set to high on the amps?

[Phreddy]

It's not a gain setting problem, and I doubt it's an earth problem.

It seems that the amps are staying powered up for a short moment after the HU powers down. What are you running to the amplifiers "remote" inputs? Is it a true remote output from the head unit, or are you running it off the accessories feed?

When the HU powers down, there can be a brief pulse of DC from the line outputs, this doesn't usually happen for a second or so, and by that time the amplifier has usually powered down as well. If for some reason the amp is staying powered up after the head unit shuts down, that explains the "pop" you're getting.

[holdenvz]

how do u make loud bass i got amp and sub but its not that loud can someome help me

[2LOUD2OLD]

the most important thing for subs is the box, ensure that you have the correct enclosure for your sub according to the sub's specifcations. a ported enclosure may give you the output you are after.
it also comes down to how loud do you want it, maybe the gear you have just wont cut it

[sxc_sound]

the remote is running straight off the head unit, the pop used to be really bad when i first installed it, but i re designed my boot install and moved the amps around and neatened up all the cables, this was to stop my interference. Since then it isn't as bad, but still quite noticeable, maybe I'll just have to get use to it lol.

[Philthy]

how do u make loud bass i got amp and sub but its not that loud can someome help me

Have you got the gains and filters on the amp set right?

[cartoonwally]

+1 to what phreddy said. Next question is, check that the amps are indeed turning off when the headunit turns off, could be something wrong with the remote setup. Also, as philthy and phreddy suggested, if its a large DC pulse on the line levels, and your filters are set low enough to pick up the DC then yeh, you'll get that going through your system.

[sxc_sound]

would a rca line filter fix the issue? or is it more in the power cable the issue

[holdenvz]

Have you got the gains and filters on the amp set right?

im not that sure lol i dont no nothing about it

[5ivespeed]

+1 check that the amps are indeed turning off when the headunit turns off.

i cant think of what its called but you can get a switch that goes on your remote wire to stop this. it usually happens when the amps not turning off. it also happens if you drive around with the headunit off.

[commsirac]

before doing to much else, actually establish that the hu a possible cause of the problem. Disconnect the rca leads from the amp, if the noise still remains on powering down, then the problem isnt hu.